Stretch release article

ABSTRACT

Provided are adhesive articles and assemblies that include a flat and at least partially elastic backing along with a patterned adhesive coating on each side of the backing. When viewed from directions perpendicular to the backing, the adhesive on one side of the backing does not substantially overlap the adhesive on the opposing side of the backing. As a result, it is possible to use a stretch removable adhesive article that uses, for example, an aggressive adhesive to provide a reliable bond but still remove cleanly and easily from delicate substrates that would otherwise be damaged or destroyed if bonded with conventional adhesive constructions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/730,125, filed Dec. 28, 2012, now allowed, the disclosure of which isincorporated by reference in its entirety herein.

FIELD OF THE INVENTION

Provided are dual-sided adhesive articles for adhering opposingsubstrates to each other. More particularly, the dual-sided adhesivearticles are stretch removable from at least one of the substrateswithout damage to that substrate.

BACKGROUND

Stretch removable adhesive articles provide temporary bonding solutionsin a wide variety of commercial and industrial applications. Theseadhesive articles can be easily removed from a bonded substrate bystretching the article lengthwise in a direction substantially parallelto the plane of the substrate. Because the adhesion substantiallydegrades as the adhesive is elongated, the stretching action enables theadhesive to be conveniently detached without damaging the underlyingsubstrate. These articles are commonly used to bond two differentsubstrates to each other, thus allowing two adhesively bonded materialsto be separated from each other without damage to either substrate.

Commercial stretch removable adhesive articles include COMMAND brandadhesive tapes sold by 3M Company, St. Paul, Minn. and POWER-STRIPSbrand self-adhesive tapes sold by Beiersdorf AG, Hamburg, Germany. Theseproducts can be optionally provided with long discrete strips of apressure sensitive adhesive with a pull tab at one end to facilitatestretching of the strips during removal. Optionally, the adhesive areascan be protected using a release liner prior to use. In some cases, itis advantageous for the adhesive to undergo inelastic deformation as itstretches to avoid sudden recoil, or “snap,” when the adhesive fullydetaches. An ancillary benefit of inelastic deformation duringstretching is that such products do not return to their original shape,thereby indicating if the product has been previously used or tamperedwith.

Adhesive tapes and films that are stretch removable can be especiallyuseful in bonding to soft and/or delicate surfaces. For example, sucharticles have been used for temporary attachment of paper articles, suchas for holding posters, signs, or other large format graphics, or evenbonding to skin in medical tape, wound or surgical dressing, athletictape, surgical drape, and medical device applications. Finally, thesearticles can also be used to facilitate attachment of other articles toclothing, as commonly used in adult incontinence pads or femininehygiene products such as absorbent sanitary napkins, which are adheredto undergarments. These types of applications pose unique challenges notonly because of the flexibility of the substrate but also the need toreconcile the demand for high levels of adhesion with the need to avoidinadvertent damage to the substrate during removal.

SUMMARY

Engineering a removable adhesive can present unique challenges withrespect to user experience. In some applications, users find that a peelaction is a more intuitive way to remove an article adhesively bonded toa substrate. Yet, detachment from the substrate does not effectivelyoccur with conventional stretch removable adhesives unless the adhesiveis stretched lengthwise in a direction substantially parallel to theplane of the substrate surface. As a result, undue force may be requiredto remove the adhesive, or even worse, adhesive residue may be left onthe surface of the substrate after removal. While this problem may beaddressed by using a less aggressive adhesive, such a solution is ofteninadequate when bonding to garments.

Products intended for adhesion to garments can face particularchallenges resulting from certain types of garment movements during use.These movements may include longitudinal and transverse extension aswell as twisting movements, which may impose stresses on the adhesive. Acommon failure mode for feminine hygiene products is the partialdetachment or shifting of the adhesive induced by twisting and shearingtype movements of the garment relative to feminine hygiene products.These movements, which often occur as a result of walking, can cause thehygiene product to slowly migrate from its intended position. If thestresses are sufficiently large, these movements can even cause theadhesive to completely detach from the undergarment. Also problematic is“bunching” of the garment, which can cause a partially detached adhesiveto buckle and become permanently adhered to itself.

It was discovered that these problems can be overcome by using anadhesive article that includes a substantially elastic backing and apatterned adhesive coating on each side. When viewed in cross-section,the adhesive on one side of the backing substantially does not overlapthe adhesive on the opposing side of the backing. As a result, it ispossible to enable a stretch removable adhesive article that uses anaggressive adhesive to provide a reliable bond and still removes cleanlyand easily from delicate substrates, such as paper or undergarments,that would otherwise be damaged or destroyed if bonded usingconventional adhesive articles. As a further benefit, these adhesivearticles display superior stretch characteristics which help avoiddetachment of the adhesive from the garment even when the garment issubjected to extreme twisting and shear type movements.

In one aspect, a method of making a feminine hygiene pad is provided,comprising: providing a flat and substantially elastic backing havingfirst and second major surfaces;

adhesively coupling a release liner to the first major surface using afirst adhesive coated according to a first two-dimensional pattern; andadhesively coupling an absorbent article to the second major surfaceusing a second adhesive coated according to a second two-dimensionaladhesive pattern, wherein the first and second patterns do notsubstantially overlap with each other when each is projected onto acommon reference plane coplanar with the backing.

In another aspect, a method of detaching from a substrate a generallyflat adhesive article is provided, the adhesive article having asubstantially elastic backing, a first adhesive extending across the topsurface according to a two-dimensional first pattern, a second adhesiveextending across the bottom surface according to a two-dimensionalsecond pattern, wherein the first and second patterns generally do notoverlap each other when viewed from above, the method comprising:stretching the backing and first adhesive along a direction generallyparallel to the backing along an area of the adhesive article that isdevoid of the second adhesive to remove the first adhesive from thesubstrate; and stretching the backing and second adhesive along adirection generally parallel to the backing along an area of theadhesive article that is devoid of the first adhesive, wherein both thefirst and second adhesives remain bonded to the backing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of a dual-sided adhesive article according toone embodiment, looking toward its top surface.

FIG. 2 shows an elevational side view of the article of FIG. 1, rotated90 degrees and looking toward its side surface.

FIG. 3 shows a plan view of a dual-sided adhesive article according toanother embodiment, looking toward its top surface.

FIGS. 4A-B show two cross-sectional side views of the article of FIG. 3,as defined by consecutive section planes indicated in FIG. 3.

FIG. 5 shows a plan view of a dual-sided adhesive article according toyet another embodiment, looking toward its top surface.

FIGS. 6A-C show three cross-sectional side views of the article of FIG.5, as defined by consecutive section planes indicated in FIG. 5.

FIG. 7 shows a plan view of a dual-sided adhesive article according toyet another embodiment, looking toward its top surface.

FIGS. 8A-C show three cross-sectional side views of the article of FIG.7, as defined by consecutive section planes indicated in FIG. 7.

FIG. 9 shows a plan view of a dual-sided adhesive assembly according toanother embodiment, looking toward its bottom surface.

FIG. 10 shows a plan view of the assembly of FIG. 9, looking toward itstop surface.

FIGS. 10A-C show fragmentary plan views for three variants of theassembly shown in FIGS. 9-10, with focus on a particular element of theassembly and looking toward its top surface.

FIG. 11 shows an elevational side view of the assembly of FIGS. 9-10,looking toward its side surface while it is removed from its underlyingsubstrate.

DETAILED DESCRIPTION

Described in further detail herein are articles and assemblies that usea stretch removable adhesive along with associated methods of making andusing the same. Stretch removable articles and assemblies, while broadlyexamined here, can be customized for any of a number of applicationsincluding medical, industrial, and consumer products. In particular,these constructions can be specialized for bonding articles to varioussubstrates, including both rigid substrates (e.g. walls) and flexiblesubstrates (e.g. clothing). These configurations can be rendered in bothsimple and compound constructions; for example, the provided articlesand assemblies can be implemented as a dual-sided tape, a substratepre-coated with such a tape, or two or more substrates coupled to eachother by such a tape. Each substrate may be either permanently ortemporarily coupled to the tape. The substrates themselves may befunctional, ornamental, or both. While particular embodiments aredescribed here by way of illustration and example, these should not bedeemed to unduly restrict the scope of the claimed invention.

An adhesive article according to one exemplary embodiment is shown inFIGS. 1 and 2, and designated by the numeral 100. In plan view, thearticle 100 is generally rectilinear as shown, but could also haverounded edge contours if desired. The article 100 is generally planarwhen relaxed, although the article 100 could optionally be convertedinto a roll for a compact storage and dispensing. The article 100includes a generally planar backing 102. As shown in FIG. 2, the backing102 has two major surfaces, a top surface 104 and a bottom surface 106.

Suitable materials for the backing 102 include polymeric sheet materialsthat display high elasticity, high strength, and high tensile strengthto function properly during stretch removal of the article 100.Exemplary backings 102 preferably have an elastic recovery of at leastabout 70 percent, at least about 80 percent, or at least about 90percent based on an elongation of 100 percent. Such backings 102 couldalso, in some embodiments, have an elastic recovery of at most about 95percent, at most about 85 percent, or at most about 70 percent based onan elongation of 100 percent.

Percent elongation=(L_(s)−L_(o))/L_(o)×100 where L_(o) is originallength L_(s) is stretched length. Also sometimes the duration of hold atstretch condition is mentioned as in stretched to 100 percent andimmediately relaxed. The equation for elastic recovery is then:

Percent recovery=(L_(s)−L_(r)/L_(o))×100, where L_(o) and L_(s) are asdefined above and

-   -   L_(r) is length after relaxation from stretch (usually a time        period is given for the relaxation such as 5 minutes).

It is also preferred that the backing 102 have a sufficient range ofelongation that enables removal of the adhesive from the underlyingsubstrate on demand. In some embodiments, the backing 102 has alengthwise elongation at break of at least about 50 percent, at leastabout 150 percent, or at least about 350 percent. In some embodiments,the lengthwise elongation at break is at most about 1,200 percent, atmost about 900 percent, or at most about 700 percent.

In preferred embodiments, the tensile strength at break of the backing102 is sufficiently high so that the backing 102 will not rupture priorto or during removal of the adhesive article 100 from the surface towhich it has been adhered. The tensile strength at break of the backing102 is preferably at least about 4.3 ksi, more preferably at least about5.3 ksi, and most preferably at least about 6.3 ksi.

Examples of materials particularly suitable for the backing 102 of thearticle 100 include any material capable of being formed into a thinfilm layer and exhibiting elastomeric properties at ambient conditions.Elastomeric means that the material will substantially resume itsoriginal shape after being stretched. The elastomer can be both pureelastomers and blends with an elastomeric phase or content that willstill exhibit substantial elastomeric properties at room temperature.

Suitable elastomers include such elastomeric polymers known to thoseskilled in the art as AB and ABA block copolymers. Star or radial blockcopolymers may also be suitable in the present invention. Elastomericblock copolymers are typically thermoplastic rubbers that have a rubberymidblock with at least two high glass transition temperature endblocks.Block copolymers are described, for example, in U.S. Pat. No. 3,562,356(Nyberg et al.); U.S. Pat. No. 3,700,633 (Wald et al.); U.S. Pat. No.4,116,917 (Eckert); and U.S. Pat. No. 4,156,673 (Eckert).

There are at least two basic classes of these polymers. In one class,the midblock is an unsaturated rubber. Examples of two types of polymersin this class are known to those skilled in the art as SBS and SIS blockcopolymers. In the other class, the midblock is a saturated olefinrubber. Examples of two types of polymers in this class are known tothose skilled in the art as SEBS and SEPS block copolymers. SIS, SBS,SEBS, and SEPS block copolymers are useful in the present invention,with SIS block copolymers being preferred because of the elastomericproperties exhibited by these polymers.

Other useful elastomeric compositions may include elastomericpolyurethanes, ethylene copolymers such as ethylene vinyl acetates,ethylene/propylene copolymer elastomers or ethylene/propylene/dieneterpolymer elastomers. Blends of these elastomers with each other orwith modifying non-elastomers may also be useful. For example, up to 50weight percent, but preferably less than 30 weight percent, of polymersmay be added such as poly(alpha-methyl)styrene, polyesters, epoxies,polyolefins, e.g., polyethylene or certain ethylene/vinyl acetates,preferably those of higher molecular weight, or coumarone-indene resin.

The backing 102 preferably has a composition that is compatible with theadhesive or adhesives used in the construction. For example, an adhesivedisposed thereon should form a strong bond with the surface of thebacking 102, thereby avoiding undesirable adhesive transfer duringstretch removal of the article 100 from a substrate. Anotherconsideration is the problem of cross-contamination which could occurwhen the backing 102 is placed in contact with certain adhesives. Insome preferred constructions, the backing 102 includes a sandwichcontruction where a protective polyolefin skin layer is disposed on eachmajor surface of an elastomeric core layer. Protective layers canprevent tackifiers in an adhesive from migrating into the elastic filmand causing the adhesive to lose tack over time.

Other aspects of elastomeric materials suitable for the backing 102 aredescribed in U.S. Pat. No. 5,376,430 (Swenson et al.) and U.S. Pat. No.6,436,529 (Deeb et al.).

The backing 102 can be made by any method of film forming presentlyknown in the art, such as extrusion, co-extrusion, solvent casting,foaming, and the like. Use of a non-woven technology to form the backing102 is also possible. The backing 102 can have any thickness so long asit possesses sufficient integrity to be easily processed and handled.Preferably, the backing 102 has a thickness ranging from about 10micrometers to 250 micrometers. In the preferred range, thinner backingscan sometimes provide easier removal than thicker ones.

Referring again to FIGS. 1 and 2, a first series of parallel adhesivestrips 108 contact and longitudinally extend across the top surface 104of the backing 102. Additionally, a second series of adhesive strips 110contact and longitudinally extend along the bottom surface 106 of thebacking 102. In FIG. 1, the second series of adhesive strips 110 can beobserved through the translucent backing 102, although this need not bethe case in general. This particular embodiment shows an asymmetricadhesive layer arrangement, with three strips 108 disposed on the topsurface 104 and four strips 110 disposed on the bottom surface 106. Moreor fewer strips may be used on either of the top or bottom surfaces 104,106.

The first strips 108 do not extend to the edges of the article 100,while the second strips 110 extend to the edges of the article 100. InFIG. 1, this is manifested by the terminal ends of the former beingspaced apart from the terminal edge of the underlying backing 102 andthe terminal ends of the latter being flush with the terminal edge ofthe backing 102. This feature can provide particular advantages ininitiating proper adhesive removal from a substrate, as will bediscussed later.

As shown, each series of adhesive strips 108, 110 extends across itsrespective top or bottom surface 104, 106 according to a pre-definedtwo-dimensional pattern. The term “pattern,” as used herein, broadlyrefers to a plurality of replicated features, or “repeat units.” Inpreferred embodiments, each two-dimensional pattern has a defined repeatunit that is replicated across the backing 102. The repeat units arefurther characterized by a repeat dimension, corresponding to theshortest distance a repeat unit is moved to superimpose on an adjacentrepeat unit of the pattern. More than one repeat dimension may exist—forexample, two different repeat dimensions may be oriented alongrespective x and y axes of the two-dimensional pattern.

In FIGS. 1 and 2, the patterns represent discrete and parallel elongatedstrips having a fixed width, length, and repeat dimension. The first andsecond patterns correspond to respective first and second series ofstrips 108, 110, and do not overlap with each other when the respectivepatterns are projected onto a common reference plane 114 coplanar withthe backing 102. As a result, areas of the backing 102 that are coatedon one surface 104, 106 of the backing are uncoated on the oppositesurface 104, 106, and vice versa. Stated inversely, this configurationavoids having regions of the backing 102 where adhesive is coated onboth sides.

As shown in FIGS. 1 and 2, the first and second patterns as projectedonto the reference plane 114 are spaced apart from each other by atransverse gap 112. As shown, the gap 112 is characterized by a gapwidth 6, and extends in a direction perpendicular to the strips 108, 110along the plane of the backing 102. Areas of the backing 102 within thegap 112 are bare; that is, these areas are not coated on either the topor bottom surfaces 104, 106 of the backing 102.

While the gap 112 here essentially represents the lateral space betweenthe nearest edges of adjacent strips 108, 110, the gap 112 more broadlyrepresents the area of separation between respective projections of theadhesive layer patterns disposed on opposite sides of the backing 102.In some embodiments, the gap width δ is not constant but variable. Forexample, if the adhesive strips are not parallel, the gap width δ wouldhave a range of values. In some embodiments, the adhesive layer patternsoverlap, resulting in a “negative” gap in these locations. When the gapwidth δ is not constant, the gap 112 could be characterized by anaverage gap width δ based on an integrated average of differential gapwidths along the perimeter of each pattern feature.

While the gap 112 can significantly affect the release characteristicsof the article 100, it is not essential. In some embodiments, forexample, there is neither a positive nor negative gap between the firstand second patterns when projected onto the reference plane 114. In this“zero gap” configuration, the projection of the second pattern on thereference plane 114 is in perfect registration with the inverse of theprojection of the first pattern. Even where the gap 112 is small, thesetwo patterns could be considered substantially in registration with eachother.

By facilitating elongation of the backing 102, the gap 112 provides auseful engineering variable to tailor stretch removal of the adhesivearticle 100 from a given substrate. Notably, when the adhesive article100 adhesively bonds two substrates to each other, areas of the backing102 within the gap 112 are not “pinned” to either substrate. As aresult, the same amount of force causes the backing 102 to stretch to agreater extent, further resulting in a greater ease of opening in a peelmode. Another benefit of the gap 112 is the reduction in unit costs tomanufacture the adhesive article 100, because less adhesive is requiredto coat the backing 102 as the gap width δ increases and coating areadecreases.

In some embodiments, the gap 112 has a gap width δ (or average gap widthδ) of at least about 10 percent, at least about 25 percent, at leastabout 50 percent, at least about 100 percent, or at least about 200percent of the repeat dimension for either the first or second pattern.In some embodiments, the gap width δ (or average gap width δ) is at mostabout 500 percent, at most about 400 percent, at most about 300 percent,at most about 250 percent, or at most about 200 percent of the repeatdimension for either the first or second pattern.

The gap 112 is inversely related to the cumulative degree of coverage ofthe first and second patterns with respect to the backing 102. In someembodiments, the adhesive coating areas defined by the first and secondpatterns collectively extend across an area representing at least about10 percent, at least about 15 percent, at least about 25 percent, atleast about 50 percent, or at least about 75 percent of the overallsurface area of the backing 102 (the combined surface area of the topand bottom surfaces 104, 106). In some embodiments, the adhesive coatingareas defined by the first and second patterns collectively extendacross an area representing at most about 95 percent, at most about 90percent, at most about 60 percent, at most about 30 percent, or at mostabout 10 percent of the overall surface area of the backing 102.

The arrangement of the coated patterns can help achieve a particularmode of removal from a given substrate. For example, the asymmetriccoating configuration in FIGS. 1 and 2 (with three adhesive strips 108opposing four adhesive strips 110) tends to induce preferential removalfrom the substrate bonded to the fewer and shorter adhesive strips 108.A similar advantage is obtained by virtue of the adhesive strips 110having terminal edges flush with that of the backing 102 and theadhesive strips 108 having terminal edges spaced apart from that of thebacking 102. The four adhesive strips 110 collectively anchor theadjacent substrate to the backing 102 as the article 100 is initiallypeeled, concentrating the peel forces against the seam between theadhesive strips 108 and the opposing substrate to initiate removal alongthat preferred interface.

In some embodiments, the first and second adhesives extend acrosssimilar overall coating areas with respect to each other on respectivetop and bottom surfaces 104, 106. In some embodiments, the firstadhesive is the majority coating and extends across at least about 30percent, at least about 40 percent, at least about 50 percent, at leastabout 60 percent, or at least about 75 percent of the top surface 104.In some embodiments, the first adhesive extends across at most about 90percent, at most about 85 percent, at most about 80 percent, at mostabout 75 percent, or at most about 70 percent of the top surface 104.

Alternatively, the coating area of the first adhesive can be quantifiedas a percentage of the coating area of the second adhesive. In someembodiments, the second adhesive is a minority coating and extendsacross a coating area of at most about 90 percent, at most about 85percent, at most about 80 percent, at most about 75 percent, or at mostabout 70 percent of the overall coating area of the first adhesive. Insome embodiments, the second adhesive extends across a coating area ofat least about 30 percent, at least about 40 percent, at least about 50percent, at least about 60 percent, or at least about 70 percent of theoverall coating area of the first adhesive.

The coating weight of the first or second adhesive, which relates toadhesive layer thickness, can be adjusted as needed based on thematerials and application. In some embodiments, the first or secondadhesive has a coating weight of at least about 5 gsm, at least about 10gsm, at least about 20 gsm, at least about 35 gsm, or at least about 50gsm of the coated area of the backing 102. In some embodiments, thefirst or second adhesive has a coating weight of at most about 100 gsm,at most about 90 gsm, at most about 75 gsm, at most about 60 gsm, or atmost about 50 gsm of the coated area of the backing 102.

In some cases, it is desirable for the first and second adhesive to havesufficient elasticity so not to interfere with the recovery of thebacking 102 when it is stretched during peel. This can be especiallybeneficial, for example, in a consumer application where the adhesivearticle 100 may require re-positioning on a garment after beingimproperly positioned on the first attempt.

The precise nature of the first and second patterns need not belimiting. While the first and second patterns define elongated stripesin FIGS. 1 and 2, many other patterns are possible. For example, asuitable pattern could include a replicated array of triangles,rectangles, circles, or any number of other two-dimensional shapes.Further, a pattern can include continuous features, discontinuousfeatures, or combination of both. Randomized patterns having replicatedfeatures arranged in an irregular two-dimensional arrangement, such as arandomized dot pattern, can also be used. Replicated features need notbe identical to each other; for example, a pattern of replicated circlesmay include circles having different diameters.

The first and second adhesive strips 108, 110 themselves are preferablycomposed of a pressure-sensitive adhesive (“PSA”). In some embodiments,the same adhesive is used for both the first and second adhesive strips108, 110. Alternatively, the first and second adhesive strips 108, 110could use different adhesives. This could be advantageous where it isdesirable to optimize at least one of the adhesives for specificperformance characteristics or end uses. Choice of adhesives could beused, for example, to facilitate preferential removal with respect toone substrate over the other.

The particular adhesion properties can be at least partially dependenton the mode of measurement. Preferred adhesion properties generallyrange from about 13 N/dm to about 200 N/dm, preferably from about 25N/dm to about 100 N/dm, at a peel angle of 180 degrees, measuredaccording to PSTC-1 and PSTC-3 and ASTM D 903-83 at a peel rate of 12.7cm/min. A backing 102 having a higher tensile strength may be used foradhesives with high peel adhesion.

PSAs suitable for this invention include tackified rubber adhesives,such as natural rubber, olefins, silicones, polyisoprene, polybutadiene,polyurethanes, styrene-isoprene-styrene and styrene-butadiene-styreneblock copolymers, and other elastomers, and tackified or untackifiedacrylic adhesives such as copolymers of isooctylacrylate and acrylicacid, which can be polymerized by radiation, solution, suspension, oremulsion techniques. Crosslinked adhesives are preferred, especiallythose PSAs crosslinked to provide high shear strengths. Particularlypreferred adhesives include those crosslinked by radiation with orwithout a chemical crosslinking agent. Adhesives that have high shearstrength provide low debonding force and can easily be removed whenstretched.

For applications such as feminine hygiene pads, it may be preferred touse tackified synthetic rubber type adhesives rather than radiation orotherwise cross-linked adhesives. Advantageously, the former adhesivescan be melted in the bulk and subsequently applied to the backing. Thesematerials include, for example, SIS block copolymer adhesives. Althoughthe styrene (“S”) domains in SIS-type adhesives are viewed as crosslinksthey are not covalent in nature and can be melted.

The adhesive article 100 can be produced by any known method forpreparing pressure-sensitive adhesive articles. For example, one or bothof the adhesive strips 108, 110 can either be directly coated onto thebacking 102, or they can be formed as a separate layer and then laterlaminated to the backing 102. As another example, one or both of theadhesive strips 108 could be coated onto a respective substrate and thenadhesively coupled to the backing 102. In one exemplary embodiment, thebacking 102 is part of a continuously conveyed web and pattern coatedusing intermittent adhesive applicators, the applicators being preciselypositioned on opposite sides of the backing 102 and operating inregistration with each other to produce the adhesive article 100. Thesame process could be used to laminate subsequently a suitable substrateto one or both sides of the article 100.

To improve adhesion of the adhesive strips 108, 110 to the backing 102,the backing 102 can optionally be pretreated prior to the coating orlaminating step by corona discharge, plasma discharge, flame treatment,electron beam irradiation, ultraviolet radiation, acid etching, and/orchemical priming. Such pretreatments can be carried out with or withoutreactive chemical adhesion promoters such as hydroxyethyl acrylate orhydroxyethyl methacrylate, or other reactive species of low molecularweight.

Alternative Geometries

A small degree of overlap between the projected first and secondpatterns representing adhesive layers on opposite sides of the backingcan be tolerated. This is demonstrated by an adhesive article 200according to another exemplary embodiment illustrated in plan view andcross-section in respective FIGS. 3 and 4A-B. Like article 100, thearticle 200 includes a generally flat, planar, and continuous elasticbacking 202, with two sets of elongated adhesive strips 208, 210contacting and extending across respective first and second majorsurfaces 204, 206 of the backing 202. As shown in FIG. 3, strips 208 areparallel with each other; likewise, strips 210 are parallel with eachother.

Unlike in the article 100, however, the opposing sets of adhesive strips208, 210 do not run parallel to each other. Instead, the adhesive strips208, 210 extend along respective directions oriented at 90 degree anglesto each other, thereby creating a grid-like configuration when viewedfrom a direction perpendicular to the backing 202. In this embodiment,the first and second patterns corresponding to first and second seriesof strips 208, 210, overlap each other at intersection points when therespective patterns are projected onto a common reference plane 214coplanar with the backing 202.

FIG. 3 highlights four distinct regions 212, 220, 222, 224 that can beidentified with respect to either the first or second major surface 204,206 of the backing 202. These include: (1) a periodic two-dimensionalarray of gap regions 212 where no coating is present on either side ofthe backing 202, (ii) first coated regions 220 where only the firststrips 208 contact the backing 202, (iii) second coated regions 222where only the second adhesive strips 210 contact the backing 202, andfinally (iv) double-coated regions 224 where both the first and secondadhesive strips 208, 210 contact the backing 202 from opposite sides.

The double-coated regions 224 coincide with areas of overlap between thefirst and second patterns when projected onto the reference plane 214.In some embodiments, the collective area of the double-coated regions224 is sufficiently small relative to the either the first or secondmajor surface 204, 206, as viewed from a direction perpendicular to thebacking 202, to enable clean stretch removal from a bonded substrate inpeel mode. Preferably, the overall area of the double-coated regions 224is less than about 50 percent, less than about 40 percent, less thanabout 30 percent, less than about 20 percent, or less than about 10percent of the overall area of the first or second major surface 204,206 as viewed from a direction perpendicular to the backing 202.

The presence of double-coated regions 224 can be significant duringstretch removal because the backing 202 (and associated adhesive) isconstrained on both surfaces 204, 206, preventing the adhesive fromstretching to reduce the force needed to break the bond to thesubstrate. Having limited localized regions where stretch removal isconstrained allows opposing substrates to be effectively “pinned” toeach other in some applications. These pinned regions act to retardadhesive detachment along the double-coated regions 224 and may bedesirable in certain applications, though not all.

Still another exemplary embodiment displaying a limited degree ofoverlap between coated adhesive patterns is shown in FIGS. 5 and 6A-C.These figures show an adhesive article 300 in which the first pattern isa regular array of discrete rectangles defining a first set of adhesiveislands 308 contacting and extending across a first major surface 304 ofa backing 302. A second pattern, identical to the first pattern buttransversely offset along the backing 302, defines a second set ofadhesive islands 310 contacting and extending across a second majorsurface 306 of the backing 302. The first and second patternscorresponding to the adhesive islands 308, 310 slightly overlap eachother when the respective patterns are projected onto a common referenceplane 314 coplanar with the backing 302. Like article 200, article 300includes gap regions 312, first and second coated regions 320, 322, anddouble-coated regions 324.

Related embodiments include articles including inverse “checkboard”-typepatterns that do not substantially overlap with each other. As anotherpossibility, a gap could be present between checkboard patterns wherethe corners of the opposing patterns are diagonally spaced apart fromeach other.

Yet another exemplary embodiment is illustrated by FIGS. 7 and 8A-C,which show an adhesive article 400 having a patterned adhesive coatingarranged in the form of concentric squares. Referring to FIG. 7, thearticle 400 has a backing 402 with first and second major surfaces 404,406 with a first pattern of open adhesive squares 408 on the first majorsurface 404 and a second pattern of closed adhesive squares 410 on thesecond major surface 406. As shown, when projected onto a commonreference plane 414, the first and second patterns of open and closedadhesive squares 408, 410 do not overlap each other. The first andsecond patterns are separated by a gap 412 having a fixed, pre-definedgap width 6′. As shown, the gap width 6′ is the same along both verticaland horizontal directions. The gap width 6′ is largely analogous to thegap width δ defined with respect to the article 100.

The adhesive squares 410 need not be closed. Optionally but not shownhere, the adhesive squares 410 of the second pattern are also “open,”but sufficiently small in size relative to the adhesive squares 408 tosatisfy the condition that there is no substantial overlap between theadhesive squares 408, 410.

Optionally and as shown, one or both adhesive patterns displayrotational symmetry to provide similar peeling performance alongdifferent directions. Referring again to FIG. 7, for example, the openand closed adhesive squares 408, 410 have a four-fold symmetry about arespective reference axis 430 extending from the geometric center of thesquares 408, 410 and perpendicular to the major surfaces 404, 406 of thebacking 402. Advantageously, this symmetry can provide identicalstretching characteristics along both vertical and horizontaldirections. Optionally but not shown, elongated rectangles having anaspect ratio other than 1:1 can also be realized to provide asymmetricstretching characteristics.

Further aspects of the articles 200, 300, 400 are largely analogous tothose already discussed with respect to article 100 and need not berepeated.

Adhesive Assemblies

The aforementioned adhesive articles can be manufactured, packaged, anddispensed in a wide assortment of configurations and assembliesdepending on the application at hand. For example, the top and bottom ofthe provided adhesive articles could be coated with liners to protectexposed adhesive surfaces. The liner acts as a release surface and canbe integrated into the packaging of the adhesive article or part of anadjoining adhesive article in a stack of adhesive articles, if desired.The adhesive articles could also be continuously manufactured, woundinto a roll, and converted for use as a dual-sided tape. This lastconfiguration could further include a dual-sided release liner as inmany conventional dual-sided tape constructions.

One or more of the described adhesive articles could come pre-attachedto a functional or ornamental article, providing a convenient way totemporarily secure the article to a given surface. As one example, theseadhesive articles could be used to secure a poster to a wall, whileavoiding damage to the wall when the poster is subsequently removed. Asstill another configuration, a given adhesive article could be used tojoin two different substrates, where it is desired at some later time toseparate the substrates from each other.

In some embodiments, the assembly includes a permanently bondedsubstrate having some degree of elasticity. This can advantageouslyallow the adhesive assembly to be detached and re-positioned on thesubstrate without distortion. For certain applications, however, it maybe beneficial to use a permanently bonded substrate that is relativelyinelastic compared with the backing, whereby permanent deformation ofthe assembly would effectively prevent its re-use.

In an exemplary application, a provided adhesive article attaches anabsorbent feminine hygiene pad to an undergarment by means of a suitablepressure-sensitive adhesive (“PSA”). A recurrent problem in thisparticular application relates to shifting of the pad when theundergarment is worn, as a result of the adhesive not holding wellenough. In another failure mode related to a poor adhesive bond, the padpartially or fully detaches from the undergarment. Partial detachmentcan allow the PSA to fold and stick to itself as a result of movementsby the wearer. While these problems can be somewhat alleviated by usinga stronger PSA, this often leads to further problems. For example, usinga PSA that holds too well can render the pad difficult to remove fromthe undergarment, damage the undergarment, or leave adhesive residue onthe undergarment after removal. All of the above outcomes lead toconsumer dissatisfaction.

The adhesive articles and assemblies described herein enable a solutionto the above dilemma FIGS. 9 and 10 show bottom and top views of anadhesive assembly 500 according to yet another embodiment. The assembly500 is a feminine hygiene pad having a back layer 550 with top andbottom surfaces 552, 554. In a preferred embodiment, the back layer 550is flexible and includes a liquid-impermeable or liquid-resistantmaterial. Contacting and extending across the bottom surface 554 of theback layer 550 is an absorbent pad 560. The absorbent pad 560 comes intocontact with the body of the wearer during use and functions to collectbodily discharges and prevent soiling of the attached undergarment.

The absorbent pad 560 may include a plurality of layers, such as apermeable topsheet and an absorbent core. Many absorbent core materialsare known in the art, including airfelt, cellulose wadding, fibratedcommunition pulp, tissue paper, and gelling materials such as thoseprovided by Grain Processing Corporation of Muscatine, Iowa. Furtheroptions and advantages are described in U.S. Pat. No. 6,200,298 (Osbornet al.).

Referring now to FIG. 10, the adhesive assembly 500 further includes adual-sided adhesive article for temporarily securing the assembly 500 toan undergarment. In this particular embodiment, the top side 550 issecured to the adhesive article 100 as earlier described and shown inFIG. 1. As illustrated, the four strips 110 adhesively couple thearticle 100 to the top surface 552 of the back layer 550. The threeadhesive strips 108 on the opposite-facing side of the backing 102 areavailable to adhesively couple the assembly 500 to the wearer'sundergarment while in use. The adhesive assembly 500 further includes apair of wings 570 having top and bottom surfaces 571, 573. The wings 570can fold over the lateral edges of the undergarment and adhesivelycouple to its opposing side for improved securement to the undergarment.

Optionally and as shown, an adhesive article 595 is disposed on thebottom surface 571 of each wing 570. The adhesive article 595 isessentially a miniature version of the adhesive article 100 havinganalogous components, options and advantages. Like the adhesive article100, each adhesive article 595 includes an elastic backing 597 andadhesive strips 596, 598, and can securely adhering the wing 570 to anundergarment surface while subsequently providing clean and easy stretchremoval in a peel mode. Surprisingly, this result was obtainedirrespective of the directionality of the peel motion relative to theadhesive strips 596, 598.

As mentioned previously, the tactile sensation in peeling the assembly500 from an undergarment can be adjusted based on the adhesive coatingpattern. FIGS. 10A-C show alternative embodiments of the article 595 onthe wings 570 of the assembly 500. As shown by articles 595′, 595″, and595′″ in these figures, the adhesive strips of these articles can beoriented along different directions (here, 90°, +45°, and −45° relativeto the strip direction in article 595) in the plane of the backing.While not shown here, the adhesive strips may also have a non-uniformwidth and/or non-uniform spacing.

In other embodiments, the assembly 500 is packaged with a release liner(not shown) that covers the adhesive strips 108, 596 and preventscontamination of exposed adhesive surfaces. This release liner can beeasily peeled away from the assembly 500 and discarded prior to use.

The disclosed adhesive articles and assemblies provide numerousadvantages over conventional adhesive attachment means for securingfeminine hygiene articles to undergarments and stretch removable tapes.First, these configurations enable use of PSAs that achieve high bondstrength to the substrate, while allowing these PSAs to detach cleanlyand easily from delicate substrates that would otherwise be damaged ordestroyed by conventional adhesive constructions. Second, the providedconfigurations show surprising resistance to adhesive failure, even whenbonded to garments subjected to severe twisting and shearingmovements—these types of movements have been observed to causespontaneous detachment of conventional adhesives. Third, the providedconfigurations preserve the above advantages even when removing in peelmode, which is more intuitive to consumers than stretching the adhesivealong a direction parallel to the substrate. Fourth, adhesive coatingweight can be substantially reduced in the provided configurationscompared with conventional adhesives, resulting in reduced manufacturingcosts.

Methods of Use

An exemplary mode of detaching a dual-sided adhesive assembly 600 from asubstrate 690 is shown in FIG. 11. The assembly 600 includes a flatdual-sided adhesive article 680 affixed to a permanently bondedsubstrate 650. Like the article 100, the article 680 includes a planarelastic backing 682 with top and bottom surfaces 604, 606, a firstadhesive 608 extending across the top surface 604 according to atwo-dimensional first pattern and a second adhesive 610 extending acrossthe bottom surface 606 according to a two-dimensional second pattern. Inthe embodiment shown, there is no overlap between the first and secondpatterns when viewed from above.

When it is desired to detach the assembly 600 from the substrate 690, auser grasps the substrate 650 and pulls it upwards in a direction awayfrom the substrate 690. As a result of this peeling motion, the firstadhesive 608 remains bonded to both the substrate 650 and the backing682, while both the backing 682 and second adhesive 610 collectivelystretch (as shown here, along a direction generally parallel to thebacking 682). This stretching takes place along an area of the article680 that is devoid of the first adhesive 608 and causes the secondadhesive 610 to remove cleanly from the substrate 690. Advantageously,the detachment operates in peel mode and therefore does not requirestretching of the backing 682 parallel to the plane of the substrate 690as with conventional stretch removable products.

As a further advantage, a wide range of peel angles can be used todetach the assembly 600 from the substrate 690. For example, the backing682 can be stretched by pulling the backing 682 away from the substrate690 at a peel angle of at least 90 degrees, at least 120 degrees, oreven at 1 east 135 degrees relative to the substrate 690.

In some embodiments, some degree of stretching of the backing 682 andthe first adhesive 608 occurs along a direction generally parallel tothe backing 682 along an area of the article 680 that is devoid of thesecond adhesive 610. Preferably the substrate 690 and the backing 682stretch collectively and remain adhered to each other, therebypreserving the integrity of the assembly 600.

Although not shown here, the backing 682 could include a non-adhesivepull tab at one end that functions as a handle to peel the backing 682from the substrate 690 directly. This has the benefit of furtherreducing risk of unintended detachment between the first adhesive 608and the backing 682.

Detachment of the adhesive articles can also be actuated along differentdirections and provide different results. For example, the permanentlybonded substrate 650 can be peeled away from the substrate 690 along adirection oriented 90 degrees from the peel direction described above.This peel mode would be achieved, for example, by removing the assembly500 from a substrate in a direction parallel to the longitudinal axis ofthe strips 108, 110. Empirically, this was observed to provide similaradvantages to the mode of detachment shown in FIG. 11, with an addedadvantage being a smoother peel (i.e. fluctuations in peel force weregreatly attenuated as a function of peel distance). This could provide asignificant advantage in user experience, particularly in consumerapplications.

In further aspects, methods of detaching adhesive articles arerecognized, with exemplary embodiments A-D herein described:

A. A method of detaching from a substrate a generally flat adhesivearticle having a substantially elastic backing, a first adhesiveextending across the top surface according to a two-dimensional firstpattern, a second adhesive extending across the bottom surface accordingto a two-dimensional second pattern, wherein the first and secondpatterns generally do not overlap each other when viewed from above, themethod comprising:

stretching the backing and first adhesive along a direction generallyparallel to the backing along an area of the adhesive article that isdevoid of the second adhesive to remove the first adhesive from thesubstrate; and

stretching the backing and second adhesive along a direction generallyparallel to the backing along an area of the adhesive article that isdevoid of the first adhesive, wherein both the first and secondadhesives remain bonded to the backing.

B. The method of embodiment A, wherein stretching the backing comprisespeeling the backing at a peel angle of at least 90 degrees relative tothe substrate.C. The method of embodiment B, wherein stretching the backing comprisespeeling the backing at a peel angle of at least 120 degrees relative tothe substrate.D. The method of any of embodiments A-C, wherein the substrate is afirst substrate and the adhesive article further comprises a secondsubstrate permanently bonded to the backing by the second adhesive.E. The method of any of embodiments A-D, wherein stretching the backingcomprises peeling the second substrate away from the first substrate.

EXAMPLES Materials

Materials used for the Examples are shown in Table 1.

TABLE 1 Materials List Material Description Kraton ™ 1161 Linear SIScopolymer, Kraton Polymers, Houston, TX Escorez ™ 1310 Aliphatichydrocarbon resin, ExxonMobile Chemical, Houston, TX 5550 oil Heavyhydrotreated naphthenic distillates, Calumet Lubricants Company,Indianapolis, IN Irganox ™ 1076 CAS 2082-79-3, BASF, Florham Park, NJ

Test Methods

All testing was conducted at constant temperature (23 deg. C.+/−2 deg.C.) and 50%+/−5% relative humidity. A universal constant rate ofextension tensile testing instrument equipped with a computer for datarecording and the required load ranges was used (Model 55564 HSavailable from Instron Engineering Corporation, Canton, Mass.). Theinstrument crosshead speed was set to 12 inches/min (30.5 cm/min).

A sample of the Example or Comparative adhesive article was appliedbetween a glass plate and a polypropylene film (180 microns thick, 191grams per square meter (gsm)) with two passes of a 4.5 lb roller. Insome cases the adhesive article was applied between the polypropylenefilm and 20 lb (9.1 kg) white copy paper, or two pieces of 20 lb (9.1kg) white copy paper.

Peel

The end of the polypropylene film was placed in the upper jaw of theInstron, while the glass plate was placed into the 135 degree stationaryjig on the Instron. The instrument was started and the stress-elongationcurve was measured. Average load (g(f)) and area under the curve(energy, mJ) were reported. A T-peel measurement (polypropylenelaminated to paper) was made for the samples which didn't include theglass plate. Unless otherwise noted, peel was performed in the directionof the strips of adhesive article.

Shear

The end of the polypropylene film was placed in the upper jaw of theInstron instrument, while the glass plate was placed into the 180 degreestationary jig on the Instron. The instrument was started and thestress-elongation curve was measured. Average load (g(f)) and area underthe curve (energy, mJ) were reported. The distance the film was pulleduntil it detached from the glass plate was also measured (cm). Unlessnoted, shear was performed in the direction of the strips of adhesivearticle.

Adhesive

The adhesive composition is shown in Table 2.

TABLE 2 Adhesive Composition Material % Kraton ™ 1161 48.0 Escorez ™1310 49.5 55500 oil 1.5 Irganox ™ 1076 1.0The materials in Table 2 were combined in a solvent mixture of 3 partstoluene/1 part heptane (30% solids), knife coated on a release liner,and dried in an oven at 65° C. for 20 minutes. Final coating weight wasapproximately 35 gsm (grams per square meter).

Elastic Backing

The elastic backing was a B-430 series elastic available from 3M Company(St. Paul, Minn.). This material is a 3-layer laminate consisting of ananisotropic elastic core and a micro-activated, non-elasticpolypropylene skin layer surrounding the core.

Example-1 (E-1)

Strips (0.635 cm wide) of adhesive on release liner were cut and adheredto the first side of the Elastic Backing. The strips were rectangularand parallel to adjacent strips which were about 0.95 cm apart. Strips(0.635 cm wide) of adhesive on release liner were then cut and adheredto the second (opposite) side of the Elastic Backing between the stripson the first side. The strips on the opposite sides of the ElasticBacking did not overlap; there was a gap of approximately 0.16 cm.

E-2 through E-5

E-2 through E-5 were prepared as in E-1 with the gaps shown in Table 4.

Comparative-1 (C-1)

A control was prepared as describe in Example-1, but the entire firstside of the Elastic Backing was covered with the adhesive on releaseliner. The strips on the second side overlapped with the adhesivecoating on the first side.

C-2 through C-4

C-2 was prepared as in C-1. C-3 and C-4 were prepared as in C1 exceptthe polypropylene was laminated to paper instead of glass.

Results

Shear and adhesion data are shown in Tables 3-5. For these samples, thepolypropylene film was pulled in the direction of the parallel strips ofadhesive.

Shear

As shown in Table 3, the elastic laminate of E-1 required a pull of 2 cmbefore delamination, while C-1 delaminated after only a 0.4 cm pull.

TABLE 3 Shear - Polypropylene Laminated to Glass Gap Avg Load EnergyPull Distance to Sample (cm) (gf) (mJ) Delamination (cm) E-1 0.16 3871978 2.0 E-2[a] 0.16 4102 963 2.2 CONTROL (one side of elastic is fulladhesive coat) C-1 No gap 2266 101 0.4 [a]adhesive backing strips were90° of shear direction

Adhesion

Table 4 shows the peel performance of E-2 to E-5, which had a nominalgap width ranging from −0.16 to 0.64 cm, compared with C-2, which had azero gap width. This data shows that the ability of the backing tostretch during the peel action reduced the adhesion forces, facilitatingpeel removal.

TABLE 4 Polypropylene Laminated to Glass Adhesion Sample Gap (cm) AvgLoad (gf) [a] Energy (mJ) [a] E-2 −0.16 405 566 E-3 0 404 576 E-4 0.16544 795 E-5 0.64 491 739 CONTROL (one side of elastic is full adhesivecoat) C-2 No gap 647 942 [a] All values are an average of 2 samplemeasurements.As shown in Table 5, an elastic backing with strips of adhesive allowcleanly releases from a sensitive material (paper), while an elasticbacking which was fully coated on one side tore the paper duringremoval.

TABLE 5 Polypropylene Laminated to Paper T-Peel Gap Avg peel EnergySample (cm) force (gf) (mJ) Comments E-6 0.16 117 132 Clean peel, nodelamination E-7 0.64 141 199 Clean peel, no delamination CONTROL (oneside of elastic is full adhesive coat) C-3 No gap 204 274 Paperdelaminated C-4 No gap 200 316 Paper delaminated

All of the patents and patent applications mentioned above are herebyexpressly incorporated into the present disclosure. The foregoinginvention has been described in some detail by way of illustration andexample for purposes of clarity and understanding. However, variousalternatives, modifications, and equivalents may be used and the abovedescription should not be taken as limiting in the scope of theinvention, which is defined by the following claims and theirequivalents.

What is claimed is:
 1. A method of making a feminine hygiene padcomprising: providing a flat and substantially elastic backing havingfirst and second major surfaces; adhesively coupling a release liner tothe first major surface using a first adhesive coated according to afirst two-dimensional pattern; and adhesively coupling an absorbentarticle to the second major surface using a second adhesive coatedaccording to a second two-dimensional adhesive pattern, wherein thefirst and second patterns do not substantially overlap with each otherwhen each is projected onto a common reference plane coplanar with thebacking, whereby areas of the backing coated by the first adhesive onthe first major surface are substantially uncoated by the secondadhesive on its opposing second major surface and areas of the backingcoated by the second adhesive on the second major surface aresubstantially uncoated by the first adhesive on its opposing first majorsurface.
 2. The method of claim 1, wherein adhesively coupling therelease liner to the first major surface comprises applying the firstadhesive to the first major surface and then laminating the first majorsurface to the release liner.
 3. The method of claim 1, whereinadhesively coupling the absorbent article to the second major surfacecomprises applying the second adhesive to the second major surface andthen laminating the second major surface to the absorbent article. 4.The method of claim 1, wherein the collective area of overlap betweenthe first and second patterns is less than 50 percent of the overallarea of the first or second major surface as viewed from a directionperpendicular to the backing.
 5. A method of detaching from a substratea generally flat adhesive article having a substantially elasticbacking, a first adhesive extending across the top surface according toa two-dimensional first pattern, a second adhesive extending across thebottom surface according to a two-dimensional second pattern, whereinthe first and second patterns generally do not overlap each other whenviewed from above, the method comprising: stretching the backing andfirst adhesive along a direction generally parallel to the backing alongan area of the adhesive article that is devoid of the second adhesive toremove the first adhesive from the substrate; and stretching the backingand second adhesive along a direction generally parallel to the backingalong an area of the adhesive article that is devoid of the firstadhesive, wherein both the first and second adhesives remain bonded tothe backing.
 6. The method of claim 5, wherein stretching the backingcomprises peeling the backing at a peel angle of at least 90 degreesrelative to the substrate.
 7. The method of claim 6, wherein stretchingthe backing comprises peeling the backing at a peel angle of at least120 degrees relative to the substrate.
 8. The method of claim 5, whereinthe substrate is a first substrate and the adhesive article furthercomprises a second substrate permanently bonded to the backing by thesecond adhesive.
 9. The method of claim 5, wherein stretching thebacking comprises peeling the second substrate away from the firstsubstrate.